616 NATHAN FASTEN 



In smear preparations stained with iron-hematoxylin and 

 counterstained with acid fuchsin, the nucleus stains black, the 

 cytoplasm reddish, while the vacuole seems to be made up of 

 two substances: (1) a ground substance which stains a heavy 

 black as if it consisted of hyaline or chitin-like substance; and 

 (2) droplets which stain reddish with acid fuchsin (figs. 57-58, 

 V). The centrosome stains black. 



As the transformation continues, the nucleus condenses still 

 more and migrates down into the cytoplasm (figs. 59-61, A''). 

 The cell now has the appearance of two parts, an upper half 

 composed of the transparent vesicle (figs. 59-61, V) and a lower 

 half made up largely of the cytoplasm (Z), in the bottom of 

 which the nucleus (N) has become condensed (figs. 59-61). 

 Figure 59, drawn from a smear preparation, gives a side view of 

 the transforming spermatid, with the vesicle, V, in the upper 

 extremity and the condensed disc-shaped nucleus, N, at the 

 opposite pole of the cell. The centrosome, C, has a median 

 position between V and N. Figure 60 is a similar view of a 

 somewhat later stage. Figure 61 is a top view of a transforming 

 spermatid in which the centrosome, C, lying above the nucleus, 

 N, is seen through the vesicle, V. 



Now the walls of the vesicle become somewhat thicker, and 

 at the same time the cytoplasmic wall becomes irregular in 

 outline. The centrosome is observed, in favorable preparations, 

 to undergo marked changes. Fine strands (figs. 62-63, C), 

 appear to radiate from it into the cytoplasm in various directions. 

 These strands are thin and stain dark with Heidenhain's iron- 

 hematoxylin, and in safranin-gentian-violet preparations they 

 stain a beautiful purple, like the centrosome. Figures 62 to 64 

 show these strands radiating like the arms of a starfish in all 

 directions. They form, so to speak, the skeleton along which 

 the flagella-like rays of the spermatozoa will be constructed. 

 Figure 62 shows an oblique section made through the vesicle 

 (F) and centrosome (C) of the transforming spermatid. The 

 centrosome (C) seems to be off to one side of the cell. Figure 

 63 is a top view, in which the radiating strands of the centro- 

 some (C) are seen through the vesicle (F). Figure 64 is a side 



